Qubit Grid Pairing and Detuning to Reduce Parasitic Coupling

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Solution Overview

Problem

Large-scale quantum computers face challenges in reducing parasitic interactions between qubits, which lead to unintended and uncontrolled couplings, causing errors in quantum computations.

Innovation Solution

Implementing a two-dimensional grid of qubits with nonadjacent paired data and measurement qubits, using specific frequency regions and entangling operation trajectories to minimize parasitic couplings, and applying echo pulses to reduce susceptibility to environmental noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If qubits are arranged in a dense two-dimensional grid to increase computational capacity, then the quantum computing system can perform more operations simultaneously, but parasitic interactions between diagonally opposed qubits increase causing computational errors

Engineering Contradiction:
Improvecomputational capacityVSAvoidcomputational accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent divides the qubit system into distinct operational groups by alternating which qubits are active during different time steps. This segmentation prevents parasitic interactions because diagonally opposed qubits are never simultaneously active and coupled, thereby maintaining computational accuracy while preserving dense grid architecture for high productivity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements periodic alternation between different qubit subsets for entangling operations. By periodically switching which qubits participate in interactions based on their spatial positions and coupling relationships, the system eliminates parasitic couplings while maintaining continuous computational progress through structured time-multiplexed operation

Inventive Principle:
Principle #19Periodic action

2Reliability

If entangling operations are performed sequentially between qubit pairs to avoid parasitic interactions, then computational accuracy is maintained, but the time required to complete algorithms increases

Engineering Contradiction:
Improvecomputational accuracyVSAvoidalgorithm execution time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent uses periodic alternation between different qubit subsets to enable parallel entangling operations. By structuring operations in periodic cycles where non-conflicting qubit pairs operate simultaneously, the system achieves both high accuracy (through avoidance of parasitic interactions) and efficient timing (through parallel execution of multiple operations per cycle)

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts which qubits are active and which are idle based on the current operational phase and spatial configuration. This dynamic control allows the system to maximize parallel operation opportunities while maintaining accurate timing control, thereby reducing total algorithm execution time without sacrificing computational accuracy

Inventive Principle:
Principle #15Dynamics

3Reliability

If qubit frequency control architecture is used to reduce parasitic interactions, then computational robustness is improved, but the complexity of frequency coordination between multiple qubits increases

Engineering Contradiction:
Improvecomputational robustnessVSAvoidfrequency control complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the frequency control problem by assigning specific frequency regions to different qubit types (data qubits versus measurement qubits) and different operational contexts. This segmentation simplifies coordination because frequencies are predetermined and assigned based on qubit role and spatial position, reducing the complexity of real-time frequency management while maintaining robust protection against parasitic interactions

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4296908B1Reducing parasitic interactions in a qubit grid
Publication Date: 2025.12.31 GOOGLE LLC
  • EP4296908B1 patent drawingFigure 1
  • EP4296908B1 patent drawingFigure 2
  • EP4296908B1 patent drawingFigure 3A

AI summary

Methods, systems, and apparatus for performing an entangling operation on a system of qubits. In one aspect, a method includes operating the system of qubits, wherein the system of qubits comprises: a plurality of first qubits, a plurality of second qubits, a plurality of qubit couplers defining nearest neighbor interactions between the first qubits and second qubits, wherein the system of qubits is arranged as a two dimensional grid and each qubit of the multiple first qubits is coupled to multiple second qubits through respective qubit couplers, and wherein operating the system of qubits comprises: pairing multiple first qubits with respective neighboring second qubits; performing an entangling operation on each paired first and second qubit in parallel, comprising detuning each second qubit in the paired first and second qubits in parallel.